As much as 90% of the collection at Brazil’s National Museum was destroyed in a devastating fire on Sunday and – compounding the disaster – the building was not insured, according to the museum’s deputy director.

Some pieces survived, including the famous Bendegó meteorite and a library of 500,000 books – including works dating back to the days of the Portuguese empire – which was kept in a separate annex, Cristiana Serejo told reporters in front of the building’s blackened shell.

Researchers who were able to enter one area of the building in Rio de Janeiro are starting to catalogue what little is left, said Serejo, who appealed to members of the public to return any items they found.

Asked if the museum was insured, she screwed up her face in mock anguish, and shook her head.

“I hope we learn from this,” she said. “Other public buildings are in the same situation.”

Two days after the museum was gutted in a fire that has traumatized Brazil, smoke still rose from the wreckage, and small fires are still breaking out, said a firefighter who declined to give his name. “It’s wood that is still burning. We are constantly throwing water on it.”

An aerial view of the museum on 3 September. Photograph: Buda Mendes/Getty Images

The scale of the destruction was clear: although the museum’s smoke-charred exterior walls are still standing – and statues still gaze out over the Quinta da Boa Vista park, little could be seen inside but piles of rubble.

Firefighters combing the wreckage on Tuesday found some bones and fragments of a skull, sparking hopes that the museum’s centerpiece – a 12,000-year-old skeleton known as “Luzia” – may have survived.

“Obviously we would love it to be Luzia but we can’t confirm this,” said Fernanda Guedes, a spokeswoman, adding that the biological anthropology area where the fragment was found also housed dozens of other skeletons.

Some porcelain and paintings have also been recovered from the ruins.

On Tuesday morning, there was a scuffle of excitement around Felipe da Silva, 29, a security guard who had found a burnt page of a book near the museum.

TV cameras and reporters jostled for pictures of the page – a text in English about Paleolithic and Mesolithic populations in Turkmenistan.

“It is an inexplicable feeling to be able to deliver something that stayed intact in this destruction,” Da Silva said.

The building has been sealed off to the public by crash barriers – some of which bore the name of Rio’s tourism agency Riotur.

Notes of protest had been taped to some of them. “A society without culture and research is a failure,” was written on one.

Yet while anger over the disaster remains intense, there was a palpable sense that many people want to rescue something from this tragedy.

Serejo said donations from other museums – and the return of pieces that had been loaned elsewhere – could help that process.

“The message is we will be alive and we will keep research on its feet,” she said.

On Monday, federal prosecutors said they had requested a police investigation into the cause of the fire.

In a statement, they said they held a meeting in June 2017 with fire chiefs and the government’s Institute of Historical and National Artistic Heritage to produce fire prevention standards. “Unfortunately over a year later the federal institutions responsible have not published the standards,” prosecutors said.

Meanwhile, Serejo confirmed that two fire hydrants had run out of water as firefighters battled the fire.